Wear resistant polycrystalline diamond (“PCD”) materials are utilized in a variety of mechanical applications. For example, PCD materials are used in drilling tools (e.g., cutting elements, gage trimmers, etc.), machining equipment, bearing apparatuses, wire-drawing machinery, cutting tools (e.g., endmills, drills, etc.), and in other mechanical apparatuses.
PCD material has found particular utility in superabrasive cutting elements such as rotary drill bits, endmills, and drills. A polycrystalline diamond compact (“PDC”) such as those used in rotary drill bits includes a PCD layer commonly known as the PCD body or table. The PCD body is formed and bonded to a substrate using a high-pressure/high-temperature (“HPHT”) process.
Conventional PDCs are normally fabricated by placing a cemented carbide substrate into a container or cartridge with a volume of diamond particles positioned on an upper surface of the cemented carbide substrate. A number of such cartridges may be loaded into an HPHT press. The substrate(s) and volume of diamond particles are then processed under HPHT conditions in the presence of a catalyst material that causes the diamond particles to bond to one another to form a matrix of bonded diamond grains defining a PCD body or table. The catalyst material is often a metal-solvent catalyst (e.g., cobalt, nickel, iron, or alloys thereof) that is used for promoting intergrowth of the diamond particles.
In one conventional approach, a constituent of the cemented carbide substrate, such as cobalt from a cobalt-cemented tungsten carbide substrate, liquefies and sweeps from a region adjacent to the volume of diamond particles into interstitial regions between the diamond particles during the HPHT process. The cobalt acts as a metal-solvent catalyst to promote intergrowth between the diamond particles, which results in the formation of a matrix of bonded diamond grains having diamond-to-diamond bonding therebetween, with interstitial regions between the bonded diamond grains being occupied by the metal-solvent catalyst.
Traditional methods of making milling tools such as drills and endmills having a PCD portion thereon have typically included forming slots in substrate, forming a PCD body in the slot in a substrate and removing the substrate back to expose the PCD body. However, such methods can result in cracking and delamination of the PCD body due to mismatches in the coefficients of thermal expansion (“CTE”) between the substrate material and the PCD body.
Despite the availability of a number of different types of PCD cutting tools, manufacturers and users of PCD cutting tools continue to seek improved PCD cutting tools.